Yargle, Tadpole of Urborg

Trample
Whenever a creature with no rules text enters the battlefield under your control, put an appendage counter on Yargle, Tadpole of Urborg.
Remove four appendage counters from Yargle:
Yargle gets +4/+0 and becomes a Frog until end
of turn.
Original Idea by BurritoGraveyard on Reddit.